Impact modified thinwall polymer compositions

ABSTRACT

Modified polymer compositions having good flowability, impact performance and modulus made from at least polyolefin (e.g., high density polyethylene or polypropylene) blended with minor amounts of either at least one homogeneous linear ethylene/C5-C20  alpha -olefin or at least one substantially linear ethylene/C3-C20  alpha -olefin polymer are disclosed. The compositions are suitable for thermoformed or molded thinwall applications such as drinking cups, lids, and food containers where the flow length to wall thickness ratios are greater than about 180:1.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to application Ser. No. 08/045,330, filedApr. 8, 1993; pending application Ser. No. 07/945,034, filed Sep. 15,1992; pending application Ser. No. 08/397,280, filed Mar. 13, 1995;pending application Ser. No. 08/194,236, filed Feb. 10, 1994; U.S. Pat.No. 5,272,236, application Ser. No. 07/776,130, filed Oct. 15, 1991; andU.S. Pat. No. 5,278,272, application Ser. No. 07/939,281, filed Sep. 2,1992.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to application Ser. No. 08/045,330, filedApr. 8, 1993; pending application Ser. No. 07/945,034, filed Sep. 15,1992; pending application Ser. No. 08/397,280, filed Mar. 13, 1995;pending application Ser. No. 08/194,236, filed Feb. 10, 1994; U.S. Pat.No. 5,272,236, application Ser. No. 07/776,130, filed Oct. 15, 1991; andU.S. Pat. No. 5,278,272, application Ser. No. 07/939,281, filed Sep. 2,1992.

FIELD OF THE INVENTION

This invention relates to polymer blend compositions having highflowability, improved impact properties and good modulus retention. Theinvention particularly relates to polyolefin blend compositionscomprising high density polyethylene (HDPE) or polypropylene blendedwith minor amounts of at least one linear or substantially linearethylene/α-olefin interpolymer wherein such compositions are useful inthinwall thermoforming and molding applications.

BACKGROUND OF THE INVENTION

For successful use in thermoforming and molding applications polymercompositions must possess a good balance of a number of importantproperties. One important property requirement for such use is goodrheological characteristics such as processability and/or highflowability. As part and mold designs become more intricate and detailedsuch as, for example, where embossed-type printing or patterns aredesired on the face of finished parts, even better flow properties arerequired to completely fill the mold, avoid short-shots and therebyfabricate high quality parts. Good processability is required to preventmelt fracture and/or insure finished parts have smooth, defect-freesurfaces. Furthermore, in contrast to the flow properties required forintricate mold design having relatively low flow length to wallthickness (L/T) ratio (e.g., about 100:1), for thinwall applications,which pertains to downgauged parts and goods having L/T ratios greaterthan 180:1, high flowability is particularly critical. Injection moldedpromotional cups provided as give-a-ways at fast-food restaurants is ancommon example of a thinwall application requiring exceptional polymercomposition rheological characteristics well beyond those ordinarilyrequired for conventional molding applications.

Good impact performance is another important polymer compositionproperty required to insure successful use in thermoforming and moldingapplications. Thermoformed and molded goods intended, for example, fordurable and storage use must have a level of impact and abuse resistancethat insures long service life and repeated use. For thermoformed andmolded containers used, for example, for refrigerated foodstuffs, goodlow temperature impact performance is also an important polymercomposition requirement.

Good topload strength which pertains to high modulus, dimensionalstability and compressive strength is still another important propertyrequirement. Good topload strength permits thermoformed and molded goodsto be conveniently stacked upon one another without having the goodsdeform or the stack itself become unstable. Good topload load strengthalso prevents containers from bulging or becoming unstable when filledwith dense items or liquids such as, for example, a tall (e.g.,16-ounce) drinking cup filled to the brim with a beverage or anone-gallon tub filled with ice cream.

Good melt strength is another important property particular tothermoforming. As such, successful thinwall thermoforming requirespolymer compositions that have good flowability and good melt strength.

In meeting the various property demands for successful thinwallthermoforming and molding, flow, melt strength, impact and toploadproperties must be carefully balanced. Structural polymer compositionproperties (such as, for example, density, branching and molecularweight) which directly affect one of the important properties caninversely and/or adversely affect one or more other properties. Forexample, it is well known that polyolefin compositions characterized ashaving lower densities have improved impact resistance relative to otherpolyolefin compositions having higher densities. Conversely, apolyolefin composition having a higher density invariably has a highermodulus relative to a lower density polyolefin composition. As such,good impact resistance and high modulus (good topload strength) aregenerally considered to be mutually exclusive polyolefin polymerproperties. As another mutually exclusive relationship pertaining toimpact resistance, it is also known that polyolefin compositions havinghigher molecular weights generally have improved impact and abuseproperties, however such compositions also generally have inferior flowproperties relative to polyolefin compositions having lower molecularweights.

High flowability and good melt strength is another relationship which isgenerally considered to be mutually exclusive. Whereas low molecularweights are generally required for high flowability, conversely, highmolecular weights are generally required for good melt strength.

Although various polymer compositions are used in thinwall applications,a need presently exists for high flow or high melt strength compositionswhich exhibit substantially improved impact properties while retaininggood topload strengths. In particular, there is a need for a polyolefincomponent polymer which at minor addition amounts effectively andsubstantially impact modifies high flow polyolefins also characterizedas having good topload strength.

SUMMARY OF THE INVENTION

Modified compositions useful in thinwall thermoforming and moldingapplications have now been discovered to have a good balance of highflowability, good impact performance and good modulus retention. Thecompositions useful for thinwall thermoforming and molding comprise

A) at least one polyolefin selected from the group consisting ofpolypropylene, high density polyethylene, medium density polyethylene,and linear low density polyethylene, wherein the ethylene polymers ofthe group are characterized as having

i. a processing index of less than or equal to about 1.0, and

ii. an I₁₀ /I₂ of at least 7.0, and

B) a minor amount, based on the total weight of the composition, of atleast one linear or substantially linear ethylene/α-olefin polymerwherein both the linear and substantially linear ethylene/α-olefinpolymers are ethylene/α-olefin interpolymers having

i. a short chain branching distribution index (SCBDI) greater than about30 percent, and

ii. a single melting point as determined using differential scanningcalorimetry (DSC)),

and wherein the substantially linear ethylene/α-olefin polymer isfurther characterized as having

iii. a melt flow ratio, I₁₀ /I₂, ≧5.63,

iv. a molecular weight distribution, M_(w) /M_(n), defined by theequation:

    M.sub.w /M.sub.n ≦(I.sub.10 /I.sub.2)-4.63,

and

v. a critical shear rate at onset of surface melt fracture of at least50 percent greater than the critical shear rate at the onset of surfacemelt fracture of a linear olefin polymer having essentially the same I₂and M_(w) /M_(n), i.e., the measured I₂ and M_(w) /M_(n) values arewithin 10 percent of each other for the two polymers.

The substantially linear ethylene/α-olefin polymer can also be furthercharacterized as having:

iii. a melt flow ratio, I₁₀ /I₂, ≧5.63,

iv. a molecular weight distribution, M_(w) /M_(n), defined by theequation:

    M.sub.w /M.sub.n ≦(I.sub.10 /I.sub.2)-4.63, and

v. a processing index (PI) less than or equal to about 70 percent of thePI of a linear olefin polymer having essentially the same I₂ and M_(w)/M_(n).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 describes the relationship between Topload Strength and 23° C.(70° F.) Dynatup Impact Strength from Examples 5, 8, 9, 11 and 13 andfrom Comparative Runs 3, 7, 10, 12, 14 and 16 as well as defined limitsof topload strength losses and level of required impact improvement.

FIG. 2 describes the relationship between Topload Strength and 23° C.(70° F.) Dynatup Impact Strength from Examples 18, 19, 21, 22, 24, 26and 27 and from Comparative Runs 17, 20, 23 and 25 as well as definedlimits of topload strength losses and level of required impactimprovement.

FIG. 3 describes the relationship between Topload Strength and 23° C.(70° F.) Dynatup Impact Strength from Examples 34, 35, 36 and 37 andfrom Comparative Runs 33a, 33b, 38 and 39 as well as the influence ofmelt index on the relationship.

FIG. 4 describes the relationship between Topload Strength and 23° C.(70° F.) Dynatup Impact Strength from Examples 34, 35, 36 and 37 andfrom Comparative Runs 33a, 33b, 38 and 39 as well as defined limits oftopload strength losses and level of required impact improvement.

DETAILED DESCRIPTION OF THE INVENTION

The novel modified composition is a high flow or high melt strengthpolymer composition which provides thermoformed or molded goods andparts having a Dynatup Impact Energy value at 23° C. (75° F.) at leastabout 25 percent, preferably at least about 30 percent, more preferablyat least about 50 percent higher than the at least one polyolefinComponent (A) and a topload strength retention value which is at leastabout 85 percent, preferably at least about 90 percent, more preferablyat least about 95 percent of the at least one polyolefin Component (A).The modified compositions are suitable for thermoformed and moldedthinwall applications where the flow length to wall thickness ratio ofthe thermoformed or molded good is at least about 180:1, preferredcompositions are suitable at L/T ratios of at least about 250:1 and mostpreferred compositions are suitable at L/T ratios of at least about300:1.

The term "topload retention retention value" as used herein refers to apercentage of topload strength reduction for a composition using thesame Component (A) polyolefin employed in the composition as the basisfor the calculation. For example, where a HDPE polymer measures atopload strength of 100 psi and modified composition comprising the HDPEmeasures a topload strength of 85 psi, the topload retention value forthe modified composition will be expressed as at least about 85 percent.

The term "homogeneous linear ethylene/α-olefin polymers" means that theolefin polymer has a homogeneous short branching distribution but doesnot have long chain branching. That is, the linear ethylene/α-olefinpolymer has an absence of long chain branching. Such polymers includelinear low density polyethylene polymers and linear high densitypolyethylene polymers and can be made using polymerization processes(e.g., as described by Elston in U.S. Pat. No. 3,645,992, the disclosureof which is incorporated herein by reference) which provide uniformbranching (i.e., homogeneously branched) distribution. Uniform branchingdistributions are those in which the comonomer is randomly distributedwithin a given interpolymer molecule and wherein substantially all ofthe interpolymer molecules have the same ethylene/comonomer ratio withinthat interpolymer. In his polymerization process, Elston uses solublevanadium catalyst systems to make such polymers, however others such asMitsui Chemical Corporation and Exxon Chemical Company have usedso-called single site catalyst systems to make polymers having a similarhomogeneous structure.

The term "homogeneous linear ethylene/α-olefin polymers" does not referto high pressure branched polyethylene which is known to those skilledin the art to have numerous long chain branches. Typically, thehomogeneous linear ethylene/α-olefin polymer is an ethylene/α-olefininterpolymer, wherein the α-olefin is at least one C₅ -C₂₀ α-olefin(e.g., 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene and the like),preferably wherein at least one of the α-olefins is 1-octene. Mostpreferably, the ethylene/α-olefin interpolymer is a copolymer ofethylene and a C5-C₂₀ α-olefin, especially an ethylene/C₄ -C₆ α-olefincopolymer.

The substantially linear ethylene/α-olefin interpolymers used in thepresent invention are not in the same class as homogeneous linearethylene/α-olefin polymers, nor heterogeneous linear ethylene/α-olefinpolymers, nor are they in the same class as traditional highly branchedlow density polyethylene. The substantially linear olefin polymersuseful in this invention surprisingly have excellent processability,even though they have relatively narrow molecular weight distributions.Even more surprising, the melt flow ratio (I₁₀ /I₂) of the substantiallylinear olefin polymers can be varied essentially independently of thepolydispersity index (i.e., molecular weight distribution (M_(w)/M_(n))). This is contrasted with conventional heterogeneously branchedlinear polyethylene resins having rheological properties such that asthe polydispersity index increases, the I₁₀ /I₂ value also increases.

Substantially linear ethylene/α-olefin polymers are homogeneous polymershaving long chain branching. The long chain branches have the samecomonomer distribution as the polymer backbone and can be as long asabout the same length as the length of the polymer backbone. The polymerbackbone is substituted with about 0.01 long chain branches/1000 carbonsto about 3 long chain branches/1000 carbons, more preferably from about0.01 long chain branches/1000 carbons to about 1 long chainbranches/1000 carbons, and especially from about 0.05 long chainbranches/1000 carbons to about 1 long chain branches/1000 carbons.

The substantially linear ethylene/α-olefin interpolymers used in thepresent invention are herein defined as in U.S. Pat. No. 5,272,236 andin U.S. Pat. No. 5,278,272. The substantially linear ethylene/α-olefininterpolymers useful for impact modifying the polyolefin (e.g., highdensity polyethylene and polypropylene) are those in which the comonomeris randomly distributed within a given interpolymer molecule and whereinsubstantially all of the interpolymer molecules have the sameethylene/comonomer ratio within that interpolymer.

Long chain branching can be determined by conventional techniques knownin the industry such ¹³ C nuclear magnetic resonance (NMR) spectroscopytechniques using, for example, the method of Randall (Rev. Macromol.Chem. Phys., C29 (2&3), p. 285-297), the disclosure of which isincorporated herein by reference. Two other methods are gel permeationchromatography coupled with a low angle laser light scattering detector(GPC-LALLS) and gel permeation chromatography coupled with adifferential viscometer detector (GPC-DV). The use of these techniquesfor long chain branch detection and the underlying theories have beenwell documented in the literature. See, e.g., Zimm, G. H. andStockmayer, W. H., J. Chem. Phys., 17, 1301 (1949) and Rudin, A., ModernMethods of Polymer Characterization, John Wiley & Sons, New York (1991)pp. 103-112, both of which are incorporated by reference.

A. Willem degroot and P. Steve Chum, both of The Dow Chemical Company,at the Oct. 4, 1994 conference of the Federation of Analytical Chemistryand Spectroscopy Society (FACSS) in St. Louis, Mo. presented datademonstrating that GPC-DV is a useful technique for quantifying thepresence of long chain branches in substantially linear ethyleneinterpolymers. In particular, degroot and Chum found that the level oflong chain branches in substantially linear ethylene homopolymer samplesmeasured using the Zimm-Stockmayer equation correlated well with thelevel of long chain branches measured using ¹³ C NMR.

Further, deGroot and Chum found that the presence of octene does notchange the hydrodynamic volume of the polyethylene samples in solutionand, as such, one can account for the molecular weight increaseattributable to octene short chain branches by knowing the mole percentoctene in the sample. By deconvoluting the contribution to molecularweight increase attributable to 1-octene short chain branches, degrootand Chum showed that GPC-DV may be used to quantify the level of longchain branches in substantially linear ethylene/octene copolymers.

degroot and Chum also showed that a plot of Log(I₂, Melt Index) as afunction of Log(GPC Weight Average Molecular Weight) as determined byGPC-DV illustrates that the long chain branching aspects (but not theextent of long branching) of substantially linear ethylene polymers arecomparable to that of high pressure, highly branched low densitypolyethylene (LDPE) and are dearly distinct from ethylene polymersproduced using Ziegler-type catalysts such as titanium complexes andordinary homogeneous catalysts such as hafnium and vanadium complexes.

For ethylene/alpha-olefin interpolymers, the long chain branch is longerthan the short chain branch that results from the incorporation of thealpha-olefin(s) into the polymer backbone. The empirical effect of thepresence of long chain branching in the substantial linearethylene/alpha-olefin interpolymers used in the invention is manifestedas enhanced rheological properties which are quantified and expressedherein in terms of gas extrusion rheometry (GER) results and/or meltflow, I₁₀ /I₂, increases.

In contrast to the term "substantially linear", the term "linear" meansthat the polymer lacks measurable or demonstrable long chain branches,i.e., the polymer is substituted with an average of less than 0.01 longbranch/1000 carbons.

The substantially linear ethylene/α-olefin interpolymers for use inimpact modifying the polyolefin in the present invention areinterpolymers of ethylene with at least one C₃ -C₂₀ α-olefin and/or C₄-C₁₈ diolefins. Copolymers of ethylene and 1-octene are especiallypreferred. The term "interpolymer" is used herein to indicate acopolymer, or a terpolymer, or the like. That is, at least one othercomonomer is polymerized with ethylene to make the interpolymer.

Other unsaturated monomers usefully copolymerized with ethylene include,for example, ethylenically unsaturated monomers, conjugated ornonconjugated dienes, polyenes, etc. Preferred comonomers include the C₃-C₂₀ α-olefins especially propene, isobutylene, 1-butene, 1-hexene,4-methyl-1-pentene, and 1-octene. Other preferred monomers includestyrene, halo- or alkyl substituted styrenes, tetrafluoroethylene,vinylbenzocyclobutane, 1,4-hexadiene, and naphthenics (e.g.,cyclopentene, cyclohexene and cyclooctene).

The density of the linear or substantially linear ethylene/α-olefininterpolymers (as measured in accordance with ASTM D-792) for use in thepresent invention is no higher than about 0.92 g/cc, generally fromabout 0.85 g/cc to about 0.91 g/cc, preferably from about 0.86 g/cc toabout 0.9 g/cc, and especially from about 0.865 g/cc to about 0.89 g/cc.

Generally, the amount of the homogeneous linear ethylene/α-olefininterpolymer or substantially linear ethylene/α-olefin polymerincorporated into the composition is from about 1 percent to about 25percent, by weight of the composition, preferably about 2 percent toabout 20 percent, by weight of the composition, and especially fromabout 5 percent to about 15 percent, by weight of the composition.

The molecular weight of the homogeneous linear ethylene/α-olefininterpolymer or substantially linear ethylene/α-olefin polymers for usein the present invention is conveniently indicated using a melt indexmeasurement according to ASTM D-1238, Condition 190° C./2.16 kg(formerly known as "Condition (E)" and also known as I₂). Melt index isinversely proportional to the molecular weight of the polymer. Thus, thehigher the molecular weight, the lower the melt index, although therelationship is not linear. The melt index for the homogeneous linearethylene/α-olefin interpolymer or substantially linear ethylene/α-olefinpolymers useful herein is generally from about 0.01 grams/10 minutes(g/10 min) to about 300 g/10 min, preferably about 15 g/10 min. to about250 g/10 min. and more preferably from about 30 g/10 min to about 200g/10 min.

Another measurement useful in characterizing the molecular weight of thehomogeneous linear ethylene/α-olefin interpolymer or the substantiallylinear ethylene/α-olefin polymers is conveniently indicated using a meltindex measurement according to ASTM D-1238, Condition 190° C./10 kg(formerly known as "Condition (N)" and also known as I₁₀). The ratio ofthe I₁₀ and the I₂ melt index terms is the melt flow ratio and isdesignated as I_(1O) /I₂. For the substantially linear ethylene/α-olefinpolymers used in the compositions of the invention, the I₁₀ /I₂ ratioindicates the degree of long chain branching, i.e., the higher the I₁₀/I₂ ratio, the more long chain branching in the polymer. The I₁₀ /I₂ratio of the substantially linear ethylene/α-olefin polymers is at leastabout 6.5, preferably at least about 7, especially at least about 8. TheI₁₀ /I₂ ratio of the linear ethylene/α-olefin polymers is generallyabout 6.

Additives such as antioxidants (e.g., hindered phenolics (e.g., Irganox®1010), phosphites (e.g., Irgafos® 168)), antiblock additives, pigments,fillers, and the like can also be included in the modified formulations,to the extent that they do not interfere with the enhanced formulationproperties discovered by Applicants.

The "rheological processing index" (PI) is the apparent viscosity (inkpoise) of a polymer measured by a gas extrusion rheometer (GER). Thegas extrusion rheometer is described by M. Shida, R. N. Shroff and L. V.Cancio in Polymer Engineering Science, Vol. 17, no. 11, p. 770 (1977),and in "Rheometers for Molten Plastics" by John Dealy, published by VanNostrand Reinhold Co. (1982) on page 97-99, both publications of whichare incorporated by reference herein in their entirety. All GERexperiments are performed at a temperature of 190° C., at nitrogenpressures between 5250 to 500 psig using a 0.0296 inch diameter,20:1^(L) /D die with an entrance angle of 180°. For the substantiallylinear ethylene/α-olefin polymers used herein, the PI is the apparentviscosity (in kpoise) of a material measured by GER at an apparent shearstress of 2.15×106 dyne/cm². The substantially linear ethyleneα-olefinpolymers used herein preferably have a PI in the range of about 0.01kpoise to about 50 kpoise, preferably about 15 kpoise or less. Thesubstantially linear ethylene/α-olefin polymers used herein have a PIless than or equal to about 70 percent of the PI of a linearethylene/α-olefin polymer at essentially the same I₂ and M_(w) /M_(n).

An apparent shear stress vs. apparent shear rate plot is used toidentify the melt fracture phenomena. According to Ramamurthy in Journalof Rheology, 30(2), 337-357, 1986, above a certain critical flow rate,the observed extrudate irregularities may be broadly classified into twomain types: surface melt fracture and gross melt fracture.

Surface melt fracture occurs under apparently steady flow conditions andranges in detail from loss of specular gloss to the more severe form of"sharkskin". In this disclosure, the onset of surface melt fracture(OSMF) is characterized at the beginning of losing extrudate gloss atwhich the surface roughness of extrudate can only be detected by 40×magnification. The critical shear rate at onset of surface melt fracturefor the substantially linear ethylene/α-olefin polymers is at least 50percent greater than the critical shear rate at the onset of surfacemelt fracture of a linear ethylene/α-olefin polymer having essentiallythe same I₂ and M_(w) /M_(n).

Gross melt fracture occurs at unsteady flow conditions and ranges indetail from regular (alternating rough and smooth, helical, etc.) torandom distortions. For commercial acceptability, (e.g., in collapsiblewater bottles), surface defects should be minimal, if not absent. Thecritical shear rate at onset of surface melt fracture (OSMF) and onsetof gross melt fracture (OGMF) will be used herein based on the changesof surface roughness and configurations of the extrudates extruded by aGER.

Both the linear and substantially linear ethylene/α-olefin polymersuseful for forming the compositions described herein have homogeneousbranching distributions. That is, the polymers are those in which thecomonomer is randomly distributed within a given interpolymer moleculeand wherein substantially all of the interpolymer molecules have thesame ethylene/comonomer ratio within that interpolymer. The homogeneityof the polymers is typically described by the SCBDI (Short Chain BranchDistribution Index) or CDBI (Composition Distribution Branch Index) andis defined as the weight percent of the polymer molecules having acomonomer content within 50 percent of the median total molar comonomercontent. The CDBI of a polymer is readily calculated from data obtainedfrom techniques known in the art, such as, for example, temperaturerising elution fractionation (abbreviated herein as "TREF") asdescribed, for example, in Wild et al, Journal of Polymer Science, Poly.Phys. Ed., Vol. 20, p. 441 (1982), in U.S. Pat. No. 4,798,081 (Hazlittet al.), or in U.S. Pat. No. 5,089,321 (Chum et al.) the disclosures ofall of which are incorporated herein by reference. The SCBDI or CDBI forthe linear and for the substantially linear olefin polymers used in thepresent invention is preferably greater than about 30 percent,especially greater than about 50 percent. The homogeneousethylene/α-olefin polymers used in this invention essentially lack ameasurable "high density" fraction as measured by the TREF technique(i.e., the homogeneous ethylene/α-olefin polymers do not contain apolymer fraction with a degree of branching less than or equal to 2methyls/1000 carbons). The homogeneous ethylene/α-olefin polymers alsodo not contain any highly short chain branched fraction (i.e., thehomogeneous ethylene/α-olefin polymers do not contain a polymer fractionwith a degree of branching equal to or more than 30 methyls/1000carbons).

The linear and substantially linear ethylene/α-olefin interpolymerproduct samples are analyzed by gel permeation chromatography (GPC) on aWaters 150 C. high temperature chromatographic unit equipped with threemixed porosity columns (Polymer Laboratories 103, 104, 105, and 106),operating at a system temperature of 140° C. The solvent is1,2,4-trichiorobenzene, from which 0.3 percent by weight solutions ofthe samples are prepared for injection. The flow rate is 1.0milliliters/minute and the injection size is 200 microliters.

The molecular weight determination is deduced by using narrow molecularweight distribution polystyrene standards (from Polymer Laboratories) inconjunction with their elution volumes. The equivalent polyethylenemolecular weights are determined by using appropriate Mark-Houwinkcoefficients for polyethylene and polystyrene (as described by Williamsand Word in Journal of Polymer Science, Polymer Letters, Vol. 6, (621)1968, incorporated herein by reference) to derive the followingequation:

    Mpolyethylene=a*(Mpolystyrene).sup.b.

In this equation, a=0.4316 and b=1.0. Weight average molecular weight,Mw, is calculated in the usual manner according to the followingformula: Mw=R wi* Mi, where wi and Mi are the weight fraction andmolecular weight, respectively, of the ith fraction eluting from the GPCcolumn.

For the linear and substantially linear ethylene/α-olefin polymers, theM_(w) /M_(n). is preferably from about 1.5 to about 2.5.

The substantially linear ethylene/α-olefin interpolymers used in thepresent invention are made by using techniques, methods, catalystsand/or co-catalyst described in pending application Ser. Nos.08/045,330, 08/397,280 and 07/945,034 and in U.S. Pat. Nos. 5,272,236and 5,278,272.

The polymerization conditions for manufacturing the substantially linearethylene/α-olefin polymers used in the present invention are generallythose useful in the solution polymerization process, although theapplication of the present invention is not limited thereto. Slurry andgas phase polymerization processes are also believed to be useful,provided the proper catalysts and polymerization conditions areemployed.

Multiple reactor polymerization processes can also be used in making thehomogeneous linear ethylene/α-olefin interpolymer or substantiallylinear ethylene/α-olefin interpolymers used in the present invention,such as those disclosed in U.S. Pat. No. 3,914,342, incorporated hereinby reference. The multiple reactors can be operated in series or inparallel, with at least one homogeneous catalyst employed in one of thereactors.

The Polyolefins Which Are Impact Modified (Component A)

Polyolefins which are beneficially impact modified by the addition ofthe homogeneous linear ethylene/α-olefin interpolymers or substantiallylinear ethylene/α-olefin interpolymers discussed herein arecharacterized as high flow or high melt strength compositions suitablefor thinwall thermoforming and molding applications. Suitablepolyolefins generally have a processing index (PI) of less than about1.0, preferably less than or equal to about 0.6, more preferably lessthan or equal to about 0.4 and most preferably less than or equal toabout 0.3. Suitable polyolefins include high density polyethylene(HDPE), polypropylene, medium density polyethylene (MDPE), linear lowdensity polyethylene (LLDPE) and ethylene carbon monoxide copolymers(ECO), ethylene/propylene carbon monoxide polymers (EPCO), linearalternating ECO copolymers such as those disclosed by Hefner an Brian W.S. Kolthammer, entitled "Improved Catalysts For The Preparation ofLinear Carbon Monoxide/Alpha Olefin Copolymers," the disclosure of whichis incorporated herein by reference, and recycled polyethylene (e.g.,post consumer recycled high density polyethylene recovered from wastebottles). Generally, at least one high density polyethylene (HDPE) ispreferred in molding applications and polypropylene is preferred inthermoforming applications.

The HDPE, MDPE and LLDPE polymers suitable for use as Component (A) areknown classes of compounds which can be produced by any well-knownsolution or particle-form polymerization process, such as slurrypolymerization and gas phase polymerization. Preferably, the HDPE, MDPEand LLDPE are produced using well-known Phillips or Ziegler typecoordination catalysts in a solution process, although metallocenecatalyst systems can also be used.

Component (A) can also be a blend of polyolefins or a blend of at leastone polyolefin with other thermoplastic. Such blends can be preparedin-situ (e.g., by having a mixture of catalysts in a singlepolymerization reactor or by using different catalysts in separatereactors connected in parallel or in series) or by physical blending ofpolymers such as by known melt or dry-blending techniques. Additionally,where Component (A) is an ethylene polymer homopolymer or anethylene/α-olefin interpolymer, the modified composition of the presentinvention itself can be manufactured in-situ using multiple reactors inseries or parallel configuration with the same or different catalysts ineach reactor. A technique for making the novel modified composition isdisclosed in pending U.S. Pat. No. 08/010,958, entitled EthyleneInterpolymerizations, which was filed Jan. 29, 1993, the disclosure ofwhich is incorporated herein in its entirety by reference. U.S. Pat. No.08/010,958 describes, inter alia, interpolymerizations of ethylene andC₃ -C₂₀ α-olefins using a homogeneous catalys in at least one reactorand a heterogeneous catalyst in at least one other reactor. The reactorscan be operated sequentially or in parallel.

The high density polyethylene (HDPE) can be an ethylene homopolymer oran interpolymer of ethylene with at least one α-olefin of from 3 to 20carbon atoms such as 1-propylene, 1-butene, 1-isobutylene,4-methyl-1-pentene, 1-hexene, 1-heptene and 1-octene. When HDPE is aninterpolymer, preferably, it is a copolymer of ethylene and 1-octene.However, most preferably, the high density polyethylene is an ethylenehomopolymer.

Suitable LLDPE and MDPE polymers are ethylene/α-olefin interpolymerswith at least one α-olefin of from 3 to 20 carbon atoms such as1-propylene, 1-butene, 1-isobutylene, 4-methyl-l-pentene, 1-hexene,1-heptene and 1-octene. When LLDPE or MDPE are employed as Component(A), preferably they are copolymers of ethylene and 1-octene.

The density of suitable HDPE, MDPE and LLDPE polymers (as measured inaccordance with ASTM D-792) generally range from about 0.92 g/cc toabout 0.96 g/cc, preferably from about 0.935 g/cc to about 0.958 g/ccand more preferably from about 0.942 g/cc to about 0.955 g/cc.

Generally, the I₂ melt index of suitable HDPE, MDPE and LLDPE polymers(as measured according to ASTM D-1238, Condition 190° C./2.16 kg,formerly known as "Condition (E)") is in the range of from about 0.1g/10 min. to about 300 g/10 min. For thermoforming applications, the I₂melt index is in the range of from about 0.1 to about 35 g/10 min.,preferably from about 0.5 to about 25 g/10 min., and more preferablyfrom about 1 g/10 min. to about 20 g/10 min. For molding applications,the 12 melt index is in the range of from about 20 g/10 minutes to about300 g/10, preferably from about 30 g/10 minutes to about 150 g/10minutes and, more preferably, from about 40 g/10 minutes to about 100g/10 minutes.

The I₁₀ /I₂ of suitable HDPE, MDPE and LLDPE polymers (where the I₁₀value is determined according to ASTM D-1238, Condition 190° C./10 kg,formerly known as "Condition (N)") is generally at least about 7.0,preferably at least about 7.5 and more preferably at least about 8.0.The molecular weight distribution (as determined by the method describedherein for linear and substantially linear ethylene/α-olefininterpolymers) of suitable HDPE, MDPE and LLDPE polymers is preferablyat least about 3, more preferably at least about 3.2 and most preferablyat least about 3.5. Additionally, to avoid excessive brittleness,suitable HDPE, MDPE and LLDPE polymer will not have a bimodal molecularweight distribution.

The novel modified composition comprises from about 75 to about 99weight percent, preferably from about 80 to about 98 weight percent, andmore preferably from about 85 to about 95 weight percent, based on thetotal weight of the composition, of Component (A).

The polypropylene is generally in the isotactic form of homopolymerpolypropylene, although other forms of polypropylene can also be used(e.g., syndiotactic or atactic). Polypropylene impact copolymers (e.g.,those wherein a secondary copolymerization step reacting ethylene withthe propylene is employed) and random copolymers (also reactor modifiedand usually containing 1.5-7 percent ethylene copolymerized with thepropylene), however, can also be used in the modified compositionsdisclosed herein. A complete discussion of various polypropylenepolymers is contained in Modern Plastics Encydopedia/89, mid October1988 Issue, Volume 65, Number 11, pp. 86-92, the entire disclosure ofwhich is incorporated herein by reference. The molecular weight of thepolypropylene for use in the present invention is conveniently indicatedusing a melt flow measurement according to ASTM D-1238, Condition 230°C./2.16 kg (formerly known as "Condition (L)" and also known as I₂).Melt flow rate is inversely proportional to the molecular weight of thepolymer. Thus, the higher the molecular weight, the lower the melt flowrate, although the relationship is not linear. The melt flow rate forthe polypropylene useful herein is generally less than about 300 g/10min. For thinwall thermoforming applications, the melt flow rate for thepolypropylene is generally from about 0.1 g/10 min to about 35 g/10 min,preferably from about 0.5 g/10 min to about 25 g/10 min, and especiallyfrom about 1 g/10 min to about 20 g/10 min. For thinwall moldingapplications the melt flow rate for the polypropylene is generally fromabout 20 g/10 min to about 100 g/10 min.

The formulations are compounded by any convenient method, including dryblending the individual components and subsequently melt mixing, eitherdirectly in the extruder used to make the finished article (e.g., a delicontainer), or by pre-melt mixing in a separate extruder (e.g., aBanbury mixer, a Haake mixer, a Brabender internal mixer, or a twinscrew extruder).

There are many types of molding operations which can be used to formuseful fabricated articles or parts from the modified compositionsdisclosed herein, including various injection molding processes (e.g.,those described in Modern Plastics Encyclopedia/89, Mid October 1988Issue, Volume 65, Number 11, pp. 264-268, "Introduction to InjectionMolding" and on pp. 217-218, "Injection Molding Thermoplastics", thedisclosures of which are incorporated herein by reference) and blowmolding processes (e.g., that described in Modern PlasticsEncydopedia/89, Mid October 1988 Issue, Volume 65, Number 11, pp.217-218, "Extrusion-Blow Molding", the disclosure of which isincorporated herein by reference) and profile extrusion. Some of thefabricated articles include drinking cups, ice cream tubs, delicontainers and lids, as well as other household and personal articles,including, for example, toys.

Tensile properties of fabricated thinwall parts and goods are measuredaccording to ASTM D-638. Flexural and tangent modulus for fabricatedthinwall parts and goods is measured according ASTM D-790. Dynatupenergy impact strength for fabricated thinwall parts and goods isdetermined in accordance with ASTM D-3763. Bruceton stair method 0° C.impact resistance for fabricated thinwall parts and goods is determinedaccording to ASTM D-2463.

Frozen free-drop impact resistance for fabricated thinwall parts andgoods is determined by filling five 12-ounce deli containers (fabricatedfrom same polymer composition) to the brim with water and freezing thewater/container for 24 hours in a ordinary household refrigerator. Afterfreezing for 24 hours, the five containers are dropped individually froma starting height of a 1/2 foot and dropped at incrementally 1/2 foothigher heights until rupture. If a container does not rupture at one 1/2foot increment after one drop, the same container is then dropped from aheight a 1/2 foot higher and so on until the container ruptures. Onceone container ruptures, the another container is then drop tested untilall five containers have been ruptured. The resistance to frozen impactis reported as the average rupture height of the five replications.

Topload strength for fabricated thinwall parts and goods is determinedusing an Instron tensiometer with the bottom jaw stationary and applyingcompressive stress until the the part or goods shows any indication oryielding or deformation. The topload strength is determined inquadruplicate and average to provide the values reported in Examples.

The following examples illustrate some of the particular embodiments ofthe present invention, but the following should not be construed to meanthe invention is limited to the particular embodiments shown.

EXAMPLES Example 1

In an evaluation to determine impact improvement and retention oftopload strength, a high flow isotatic polypropylene homopolymer havinga density of about 0.90 g/cc and a 2.2 MFR and supplied commercially byAmoco Polymers under the designation PP 50-6219 was thoroughly dryblended with 5 percent (by weight of the total blend) of a substantiallylinear ethylene/1-octene copolymer made by a solution polymerizationprocess using a constrained geometry catalyst and having a density ofabout 0.8965 g/cc and a I₂ melt index of about 0.90 g/10 min. The blendcomposition is fabricated into 12-ounce deli containers having a 380:1L/T and an 11-mil sidewall thickness using a OMV horizontal thermoformerfitted with 12 forming cavities. The containers were free of surfacedefects, the frozen free-drop impact resistance of the containers was1.9 ft and the topload strength of the containers was 45 lbs.

Comparative Run 2

The same evaluation as conducted for Example 1 is repeated except theisotactic polypropylene homopolymer is not dry-blend any other polymer.The containers were free of surface defects, the frozen free-drop impactresistance of the containers was 1.3 ft and the topload strength of thecontainers was 48 lbs.

From these evaluations it can be seen that the addition of a minoramount of the substantially ethylene/1-octene copolymer substantiallyimproves the low temperature impact resistance of the polypropylene(i.e., the improvement is about 46 percent) while maintaining a goodtopload strength (i.e., the topload strength retention value is about 94percent).

Examples 4, 5, 8, 9, 11, 13 and 15 and Comparative Runs 3, 6, 7, 10, 14and 16

In another evaluation, a high flow high density polyethylene copolymerof ethylene and 1-octene is made by a solution polymerization processusing Ziegler type catalysts and two reactors in series. The reactorsplit is such that about 15 weight percent of the copolymer is made inthe first reactor as a very broad molecular weight distribution polymerfraction. The reactors are controlled to provide the followingproperties: an I₂ melt index of about 78.6 g/10 min., a density of about0.942 g/cc, a monomodal molecular weight distribution of about 3.3 andan I₁₀ /I₂ of about 8.5. The high density polyethylene copolymer is dryblended with four different substantially linear ethylene/1-octenecopolymers made by a solution polymerization process using a constrainedgeometry catalyst. These blends as well as the HDPE without any modifieradded (Comparative Run 3) are fabricated on a Husky XL22P injectionmolder equipped with a four-cavity mold at a 510° F. barrel temperatureand a 60° F. mold temperature into 28-ounce deli cups having a 225:1 L/Tratio and a 26-mil wall thickness. The properties of the fabricated delicups are shown in Table 1.

                                      TABLE 1                                     __________________________________________________________________________             Substantially      Dynatup                                                                            Topload                                           HDPE.sup.a                                                                        Linear  Melt Index                                                                          Density                                                                            Impact                                                                             Strength                                     Sample                                                                             wt. %                                                                             Polymer wt. %                                                                         I.sub.2, g/10 min                                                                   g/cc lbs. lbs.                                         __________________________________________________________________________    Compar.                                                                            100 0       78.6  0.942                                                                              26   102.8                                        Run 3                                                                         Ex. 4                                                                              95   5.sup.b                                                                              77.6  0.9394                                                                             87.65                                                                              ND                                           Ex. 5                                                                              90  10.sup.b                                                                              74.1  0.9364                                                                             81.77                                                                              98.03                                        Comp.                                                                              85  15.sup.b                                                                              ND    ND   ND   77.54                                        Run 6                                                                         Comp.                                                                              75  25.sup.b                                                                              63.1  0.930                                                                              77.76                                                                              71.64                                        Run 7                                                                         Ex. 8                                                                              95   5.sup.c                                                                              70.3  0.938                                                                              34.64                                                                              94.16                                        Ex. 9                                                                              90  10.sup.c                                                                              72.8  0.938                                                                              55.34                                                                              93.54                                        Comp.                                                                              75  25.sup.c                                                                              60.5   .0934                                                                             68.96                                                                              76.93                                        Run 10                                                                        Ex. 11                                                                             95   5.sup.d                                                                              63.0  0.938                                                                              72.52                                                                              102.8                                        Comp.                                                                              80  20.sup.d                                                                              32.0  0.931                                                                              80.19                                                                              80.7                                         Run 12                                                                        Ex. 13                                                                             95   5.sup.e                                                                              69.4  0.938                                                                              31.7 98.74                                        Comp.                                                                              90  10.sup.e                                                                              76.3  0.938                                                                              19.33                                                                              104.9                                        Run 14                                                                        Ex. 15                                                                             85  15.sup.e                                                                              ND    ND   ND   85.34                                        Comp.                                                                              75  25.sup.e                                                                              49.8  0.934                                                                              78.13                                                                              78.84                                        Run. 16                                                                       __________________________________________________________________________     .sup.a The HDPE is a high flow ethylene/1octene copolymer made in a           solution polymerization process using Zieglertype catalyst and two            reactors operated in series.                                                  .sup.b The substantially linear ethylene polymer is a copolymer of            ethylene and 1octene made by a solution polymerization process using a        constrained geometry catalyst system and havings about a 30 g/10 min.         I.sub.2 melt index and about a 0.885 g/cc density.                            .sup.c The substantially linear ethylene polymer is a copolymer of            ethylene and 1octene made by a solution polymerization process using a        constrained geometry catalyst system and having about a 30 g/10 min.          I.sub.2 melt index and a about 0.913 g/cc density.                            .sup.d The substantially linear ethylene polymer is a copolymer of            ethylene and 1octene made by a solution polymerization process using a        constrained geometry catalyst system and having about a 1 g/10 min.           I.sub.2 melt index and a about 0.885 g/cc density.                            .sup.e The substantially linear ethylene polymer is a copolymer of            ethylene and 1octene made by a solution polymerization process using a        constrained geometry catalyst system and having about a 30 g/10 min.          I.sub.2 melt index and a about 0.902 g/cc density.                            ND = not determined.                                                     

FIG. 1 shows that Examples 4, 5, 8, 9, 11, 13 and 15 all show at leastabout 25 percent higher impact resistance than the based high densitypolyethylene copolymer while retaining at least about 85 percent oftopload strength of the HDPE copolymer. Conversely, FIG. 1 shows thatComparative Runs 6, 7, 10 and 16 all impart improved impact resistanceby adversely affecting topload strength. Comparative Run 14 actuallyimproved topload strength, however, impact resistance deteriorated.

Examples 18, 19, 21, 22, 24, 26 and 27 and Comparative Runs 17, 20, 23and 25

In another evaluation, another high flow high density polyethylenecopolymer of ethylene and 1-octene is made by a solution polymerizationprocess using Ziegler type catalysts and two reactors in series. Thereactor split is such that about 15 weight percent of the copolymer ismade in the first reactor as a very broad molecular weight distributionpolymer fraction. The reactors are controlled to provide the followingproperties: an I₂ melt index of about 54.4 g/10 min., a density of about0.941 g/cc, a monomodal molecular weight distribution of about 3.2 andan I₁₀ /I₂ of about 8.5. The high density polyethylene copolymer is dryblended with four different substantially linear ethylene/1-octenecopolymers made by a solution polymerization process using a constrainedgeometry catalyst. These blends as well as the HDPE without any modifieradded (Comparative Run 17) are fabricated on a Husky XL22P injectionmolder equipped with a four-cavity mold at a 510° F. barrel temperatureand a 60° F. mold temperature into 28-ounce deli cups having a 225:1 L/Tratio and a 26mil wall thickness. The properties of the fabricated delicups are shown in Table 2. The relationships between impact performanceand topload retention for these Examples and Comparative Runs are shownin FIG. 2.

                                      TABLE 2                                     __________________________________________________________________________             Substantially      Dynatup                                                                            Topload                                           HDPE.sup.a                                                                        Linear  Melt Index                                                                          Density                                                                            Impact                                                                             Strength                                     Sample                                                                             wt. %                                                                             Polymer wt. %                                                                         I.sub.2, g/10 min                                                                   g/cc lbs. lbs.                                         __________________________________________________________________________    Compar.                                                                            100 0       54.4  0.941                                                                              35.03                                                                              117.2                                        Run 17                                                                        Ex. 18                                                                             95   5.sup.b                                                                              52.9  0.940                                                                              43.33                                                                              105.9                                        Ex. 19                                                                             90  10.sup.b                                                                              54.7  0.937                                                                              82.05                                                                              100.8                                        Comp.                                                                              75  25.sup.b                                                                              48.0  0.931                                                                              79.36                                                                              75.14                                        Run 20                                                                        Ex. 21                                                                             95   5.sup.c                                                                              46.9  0.939                                                                              52.71                                                                              103.4                                        Ex. 22                                                                             90  10.sup.c                                                                              53.0  0.936                                                                              69.78                                                                              89.22                                        Comp.                                                                              75  25.sup.c                                                                              42.8   .0933                                                                             81.35                                                                              80.11                                        Run 23                                                                        Ex. 24                                                                             95   5.sup.d                                                                              39.2  0.938                                                                              75.55                                                                              105.8                                        Comp.                                                                              80  20.sup.d                                                                              21.2  0.931                                                                              89.51                                                                              85.56                                        Run 25                                                                        Ex. 26                                                                             95   5.sup.e                                                                              52.56 0.939                                                                              57.51                                                                              115.5                                        Ex. 27                                                                             90  10.sup.e                                                                              51.86 0.937                                                                              66.53                                                                              98.57                                        __________________________________________________________________________     .sup.a The HDPE is a high flow ethylene/1octene copolymer made in a           solution polymerization process using Zieglertype catalyst and two            reactors operated in series.                                                  .sup.b The substantially linear ethylene polymer is a copolymer of            ethylene and 1octene made by a solution polymerization process using a        constrained geometry catalyst system and havings about a 30 g/10 min.         I.sub.2 melt index and about a 0.885 g/cc density.                            .sup.c The substantially linear ethylene polymer is a copolymer of            ethylene and 1octene made by a solution polymerization process using a        constrained geometry catalyst system and having about a 30 g/10 min.          I.sub.2 melt index and a about 0.913 g/cc density.                            .sup.d The substantially linear ethylene polymer is a copolymer of            ethylene and 1octene made by a solution polymerization process using a        constrained geometry catalyst system and having about a 1 g/10 min.           I.sub.2 melt index and a about 0.885 g/cc density.                            .sup.e The substantially linear ethylene polymer is a copolymer of            ethylene and 1octene made by a solution polymerization process using a        constrained geometry catalyst system and having about a 30 g/10 min.          I.sub.2 melt index and a about 0.902 g/cc density.                            ND = not determined.                                                     

In another evaluation, the same high flow high density polyethylenecopolymer used as Comparative Run 3 is dry blended with a substantiallylinear ethylene/1-octene copolymers made by a solution polymerizationprocess using a constrained geometry catalyst at three different weightpercent levels. The HDPE copolymer is also dry blended with aheterogeneously branched ultra low density linear ethylene/1-octenecopolymer made by a solution polymerization process using Ziegler-typecatalyst. These blends as well as the HDPE without any modifier added(Comparative Run 28) are fabricated on a Husky XL22P injection molderequipped with a four-cavity mold at a 490° F. barrel temperature and a60° F. mold temperature into 28-ounce containers having a 185:1 L/Tratio and a 36-mil wall thickness. The properties of the fabricatedcontainers are shown in Table 3.

                  TABLE 3                                                         ______________________________________                                                                     Polymer or     Tan                                              Mod-   Part   Composition                                                                           Dynatup                                                                              Mod-                                     HDPE.sup.a                                                                            ifier  Density,                                                                             Density Impact ulus                              Sample wt. %   wt. %  g/cc   g/cc    lbs.   psi                               ______________________________________                                        Compar.                                                                              100     0      0.950  0.942   50     197                               Run 28                                                                        Ex. 29 95       5.sup.b                                                                             0.940  0.948   75     190                               Ex. 30 90      10.sup.b                                                                             0.940  0.946   80     184                               Ex. 31 85      15.sup.b                                                                             0.936  0.943   90     174                               Comp.  85      15.sup.c                                                                             0.937  0.944   73     152                               Run 32                                                                        ______________________________________                                         .sup.a The HDPE is a high flow ethylene/1octene copolymer made in a           solution polymerization process using Zieglertype catalyst and two            reactors operated in series.                                                  .sup.b The substantially linear ethylene polymer is a copolymer of            ethylene and 1octene made by a solution polymerization process using a        constrained geometry catalyst system and havings about a 30 g/10 min.         I.sub.2 melt index, about a 0.902 g/cc density and about a 7 I.sub.10         /I.sub.2.                                                                     .sup.c The heterogeneously branched ultra low density linear                  ethylene/1octene (ULDPE) copolymer made by a solution polymerization          process using a Zieglertype catalyst system and having about a 6 g/10 min     I.sub.2 melt index, about a 0.911 g/cc density and about a 8 I.sub.10         /I.sub.2.                                                                

Table 3 shows that although the UDLPE copolymer significantly improvedimpact performance (Comparative Run 32), at a 15 weight percent additionamount, its modulus retention value was undesirably low at 77 percent.Conversely, Table 3 shows the substantially linear ethylene interpolymerprovides more efficient impact modification without significant moduluslosses (i.e., modulus losses are less than 15 percent for Examples 29-31and percent improvements relative to Comparative Run 32 are higher).

In another evaluation, containers were made from reactor producedpolymer mixtures, a dry blended polymer mixture, a melt compoundedpolymer mixture, three unmodified (control) high flow injection moldingresins supplied commercially by The Dow Chemical Company under thedesignation IP-40 and IP-60, and an unmodified (control) high densitypolyethylene resin supplied commercially by The Dow Chemical Companyunder the designation HDPE 65053. Table 4 shows data for the resins andthe fabricated containers. FIG. 3 describes the relationships betweenTopload Strength and 23° C. (70° F.) Dynatup Impact Strength for thevarious containers as well as the influence of melt index on therelationships. FIG. 4 describes the relationships between ToploadStrength and 23° C. (70° F.) Dynatup Impact Strength for the variouscontainers as well as defined limits of topload strength losses andlevel of required impact improvement.

                                      TABLE 4                                     __________________________________________________________________________               Dynatup                                                                            Bruceton       Part                                                                              Flexural                                         Processing                                                                         Impact,                                                                            Frozen                                                                             Tensile                                                                            Topload,                                                                           Density,                                                                          Modulus,                                   Sample*                                                                             Index, kP                                                                          lbs. Drop, ft.                                                                          Yield, psi                                                                         psi  g/cc                                                                              psi                                        __________________________________________________________________________    Comp. 33a                                                                           0.25 39   5.15 2,670                                                                              123  0.9407                                                                            206,440                                    Comp. 33b                                                                           0.25 37   ND   2,690                                                                              121  0.9415                                                                            216,700                                    Ex. 34                                                                              0.18 54   5.05 2,640                                                                              134  0.9443                                                                            222,000                                    Ex. 35                                                                              0.29 69   6.75 2,540                                                                              110  0.9378                                                                            152,000                                    Ex. 36                                                                              0.26 50   6.00 2,900                                                                              120  0.9433                                                                            201,380                                    Ex. 37                                                                              0.21 58   5.63 2,750                                                                              124  0.9424                                                                            190,000                                    Comp. 38                                                                            0.37 60   8.58 2,795                                                                              123  0.9412                                                                            190,000                                    Comp. 39                                                                            0.30 62   6.42 2,700                                                                              125  0.9425                                                                            187,000                                    __________________________________________________________________________     *Comparative Runs 33a and 33b are unmodified high flow injection molding      resins having I.sub.2 melt indexes of about 60 g/10 minutes, densities of     about 0.952 g/cc and are supplied commercially by The Dow Chemical Compan     under the designation IP60.                                                   Example 34 is a polymer mixture having a final I.sub.2 melt index of 55       g/10 minutes that was manufactured with a two reactor configuration where     the first reactor produced 15 weight percent of the total polymer using a     constrained geometry catalyst and the fraction had a 4 I.sub.2 melt index     and a 0.917 g/cc density and the second reactor produced 85 weight percen     of the total polymer using a conventional high efficiency Ziegler catalys     system.                                                                       Example 35 is a polymer mixture having a final I.sub.2 melt index of 55       g/10 minutes that was prepared by dry tumble blending 15 weight percent o     a substantially linear ethylene polymer manufactured with a constrained       geometry catalyst system and having an I.sub.2 melt index of 30 g/10          minutes and a density of 0.902 g/cc with 85 weight percent of ethylene        polymer having an I.sub.2 melt index of 60 g/10 minutes and a density of      0.956 g/cc.                                                                   Example 36 is a polymer mixture having a final I.sub.2 melt index of 58       g/10 minutes that was prepared by melt compounding on a 8 inch, 20:1 L/D      Farrel extruder equipped with 215 psi steam 10 weight percent of a            substantially linear ethylene polymer manufactured with a constrained         geometry catalyst system and having an I.sub.2 melt index of 30 g/10          minutes and a density of 0.902 g/cc with 90 weight percent of ethylene        polymer having an I.sub.2 melt index of 60 g/10 minutes and a density of      0.956 g/cc.                                                                   Example 37 is a polymer mixture having a final I.sub.2 melt index of 36       g/10 minutes and a relatively broad molecular weight distribution (MWD)       that was manufactured with a two reactor configuration where the first        reactor produced 15 weight percent of the total polymer using a               constrained geometry catalyst and the fraction had a 4 I.sub.2 melt index     and a 0.917 g/cc density and the second reactor produced 85 weight percen     of the total polymer using a conventional high efficiency Ziegler catalys     system.                                                                       Comparative Run 38 is an unmodified high flow injection molding resins        having an I.sub.2 melt index of about 40 g/10 minutes, density of about       0.952 g/cc and is supplied commercially by The Dow Chemical Company under     the designation IP40.                                                         Comparative Run 39 is an unmodified high density polyethylene resins          having an I.sub.2 melt index of about 65 g/10 minutes, density of about       0.953 g/cc and is supplied commercially by The Dow Chemical Company under     the designation HDPE 65053N.                                             

What is claimed is:
 1. A high flow, thinwall polymer compositioncharacterized as having a rheology wherein the composition isthermoformable and moldable at a flow length to wall thickness ratio ofequal to or greater than 250:1, comprising or made fromA) from about 75to about 99 weight percent, based on the total weight of thecomposition, of at least one polyolefin selected from the groupconsisting of polypropylene, high density polyethylene, medium densitypolyethylene, and linear low density polyethylene, wherein the polymersof the group are characterized as having a processing index of less thanor equal to about 0.6 kpoise under loads of 500 to 5250 psig nitrogenpressure at 190° C. as measured using a gas extrusion rheometer whichhas a 0.0296 inch diameter and a 20:1 L/D die with a 180° entranceangle, and ethylene polymers of the group are characterized as having:i.an I₁ /I₂ of at least 7.0, and ii. a density in the range of from about0.92 grams/cubic centimeter to about 0.96 grams/cubic centimeter, and B)from about 1 to about 25 weight percent, based on the total weight ofthe composition, of at least one substantially linear ethylene/α-olefinpolymer characterized as havingi. a short chain branching distributionindex (SCBDI) greater than about 30 percent, and ii. a single meltingpoint as determined using differential scanning calorimetry (DSC), iii.a melt flow ratio, I₁₀ /I₂, ≧5.63, iv. a molecular weight distribution,M_(w) /M_(n), defined by the equation:

    M.sub.w /M.sub.n <(I.sub.10 /I.sub.2)-4.63,

v. a critical shear rate at onset of surface melt fracture of at least50 percent greater than the critical shear rate at the onset of surfacemelt fracture of a linear olefin polymer having essentially the same I₂and M_(w) /M_(n), and vi. a density in the range of from about 0.85grams/cubic centimeter to about 0.91 grams/cubic centimeter.
 2. A highflow, thinwall polymer composition characterized as having a rheologywherein the composition is moldable at a flow length to wall thicknessratio of equal to or greater than 250:1, comprising or made fromA) fromabout 75 to about 99 weight percent, based on the total weight of thecomposition, of at least one polyolefin selected from the groupconsisting of high density polyethylene, medium density polyethylene,and linear low density polyethylene, wherein all polymers of the groupare characterized as havingi. a processing index of less than or equalto about 0.6 kpoise under loads of 500 to 5250 psig nitrogen pressure at190° C. as measured using a gas extrusion rheometer which has a 0.0296inch diameter and a 20:1 L/D die with a 180° entrance angle, ii. an I₁₀/I₂ of at least 7.0, and iii. a density in the range of from about 0.92grams/cubic centimeter to about 0.96 grams/cubic centimeter, and B) fromabout 1 to about 25 weight percent, based on the total weight of thecomposition, of at least one substantially linear ethylene/α-olefinpolymer characterized as having:i. a short chain branching distributionindex (SCBDI) greater than about 30 percent, and ii. a single meltingpoint as determined using differential scanning calorimetry (DSC), iii.a melt flow ratio, I₁₀ /I₂, ≧5.63, iv. a molecular weight distribution,Mw/Mn, defined by the equation:

    M.sub.w /M.sub.n ≦(I.sub.10 /I.sub.2 -4.63,

v. a critical shear rate at onset of surface melt fracture of at least50 percent greater than the critical shear rate at the onset of surfacemelt fracture of a linear olefin polymer having essentially the same I₂and M_(w) /M_(n), and vi. a density in the range of from about 0.85grams/cubic centimeter to about 0.91 grams/cubic centimeter.
 3. Thecomposition of claims 1 or 2 wherein the I₁₀ /I₂ of Component (B) is atleast about
 7. 4. The composition of claims 1 or 2 wherein the I₁₀ /I₂of Component (B) is at least about
 8. 5. The composition of claims 1 or2 wherein Component (B) is a copolymer of ethylene and at least one C₃-C₂₀ α-olefin.
 6. The composition of claims 1 or 2 wherein of Component(B) is a copolymer of ethylene and 1-ocetene.
 7. The composition ofclaims 1 or 2 wherein the substantially linear ethylene/α-olefin polymerhas from about 0.01 to about 3 long chain branches/1000 carbons alongthe polymer backbone.
 8. The composition of claims 1 or 2 wherein theα-olefin is C₄ -C₆.
 9. The composition of claims 1 or 2 wherein thecomposition is further characterized as having a Dynatup Impact Energyvalue at 23° C. (75° F.) at least about 25 percent higher than the atleast one polyolefin Component (A) and a topload strength retentionvalue at least about 85 percent relative to the at least one polyolefinComponent (A).
 10. The composition of claims 1 or 2 wherein the at leastone polyolefin is a high density polyethylene homopolymer having an I₁₀/I₂ of at least about 7.5 and a molecular weight distribution asdetermined by gel permeation chromatography (GPC) of at least about 3.11. A fabricated article made from the composition of claims 1 or
 2. 12.A fabricated article made from the composition of claims 1 or
 3. 13. Thefabricated article of claim 12, manufactured by an injection moldingprocess.
 14. The fabricated article of claim 12, wherein the article hasa flow length to wall thickness of at least about 250:1.